View Full Version : Reducing ASDA - effect on operations


NotaLOT
23rd Jul 2010, 11:49
Dear All,

I am trying to get my head around the concepts of TORA and ASDA and in particular this one question... (by the way I am not a pilot)

I have a runway where the ASDA is currently greater than TORA/TODA. Now due to some runway works, the ASDA length may be reduced (although it will still be greater than the TORA/TODA by about 10%). TORA/TODA will remain the same as currently.

Does a reduction in ASDA imply that there will be limitations in operations (as in the maximum weight with which one can take off), or is TORA/TODA the main criterion for calculations of weight? In other words, since the TORA/TODA remain the same, there will be no operational limitations even though the ASDA is reduced?

I will be most grateful for your help on this!



alatriste
23rd Jul 2010, 12:19
hey!

If ASDA is greater than TORA=TODA that means that the stopway is longer than the clearway.
Taking credit of a stopway allows higher V1 values, that reduces TODR and TORR therefor max operational take off weight is increased.
If stopway lenght is shortened, cause of work in progress, the weight increased will be not that big although it will be higher than when not taking credit of any SWY at all.
The above is true as long as you operated as a non balanced field criteria looking for an optimized take off weight. (most of operators do it).

BizJetJock
23rd Jul 2010, 12:21
As most things in life - it depends!!:}
The majority of aircraft, and all the ones I am familiar with, are unlikely to be affected if the reduced ASDA is still greater than TODA. I can not, however, claim to be an expert on all types and I am sure someone will be able to dig up an example where this is not the case.

Hope that helps!

FE Hoppy
23rd Jul 2010, 12:28
hey!

If ASDA is greater than TORA=TODA that means that the stopway is longer than the clearway.
Taking credit of a stopway allows higher V1 values, that reduces TODR and TORR therefor max operational take off weight is increased.
If stopway lenght is shortened, cause of work in progress, the weight increased will be not that big although it will be higher than when not taking credit of any SWY at all.
The above is true as long as you operated as a non balanced field criteria looking for an optimized take off weight. (most of operators do it).
^^^^^^^^^^^^^^^^^THIS^^^^^^^^^^^^^^^^^^^^^^^^^^^

But only in the case when the MTOW is Field Length limited.

john_tullamarine
23rd Jul 2010, 12:30
All limitations must be considered separately.

A reduction in ASDA will only become limiting if it results in the separate calculations revealing that the ASDA limited weight is the lowest of all the various limitations (not just the ones you have cited).

Thus, if the original RTOW was

(a) ASDA-limited, it is a fair bet that the ASDA will remain limiting

(b) not ASDA-limited, then one might anticipate that it may, at some stage, become limiting as the value is reduced.

One doesn't often see ASDA > TODA and, generally, one doesn't expect to see TODA = TORA

Not always useful to try and generalise in performance work ...

Old Smokey
24th Jul 2010, 03:06
I've never seen ASDA>TODA, perhaps as J_T suggests, it may exist in rare circumstances. From my point of view, if the ASDA surface is good enough to stop the aircraft upon, then it's certainly good enough to fly over, and TODA should at least equal ASDA.

J_T quoted "All limitations must be considered separately.".
I'm in total agreement, being a very unbalanced individual, but be aware J_T, there's a certain VERY BALANCED individual lurking "out there" in the desert dunes, who will reduce TORA, TODA, and ASDA to ONE figure for his very balanced operations. I can just imagine him right now, at the keyboard, signing in, just got to mu....., standby for incoming:eek:

Regards,

Old Smokey

FE Hoppy
24th Jul 2010, 14:43
@<hidden> and OS
Is there a limit to the extent of a stopway? I recall 50% of TORA for Clearway but don't recall a similar limit for stop.

I'm just musing over the idea of ASDA being longer than TODA and somewhere like Edwards AFB springs to mind as there is miles and miles of salt flat which could be declared stopway.

It's purely theoretical of course but I'm a little bored today :-)

ant1
24th Jul 2010, 17:03
FH, The limit for stopway is V1<=Vr.

OS, ASDA>TODA if there is a stopway that does not meet the clearway criteria (500ft wide, etc.) if such a thing exists anywhere on earth.

john_tullamarine
25th Jul 2010, 20:38
Only recall one runway for which ASDA>TODA - in Australia - but, for the life of me, can't bring the location to mind. Never did find out the reason why ..

there's a certain VERY BALANCED individual

he's now flying for a crust so his number crunching is a tad curtailed.

Old Smokey
26th Jul 2010, 03:27
J_T,

I've done about 50% of my airport analyses in Australia, and haven't encountered ASDA>TODA, I'd appreciate your naming the one airport you found if you can recall it, just out of curiosity:)

ant1,

Thank you, I had not considered the lateral splay in the discussion. It does make sense that a reduced lateral splay could generate a suitable ASDA>TODA.

At least in the Australian environment excessively long CWY and SWY are merely bonuses for a safer operation, as RESA (Runway End Safety Area) comes into play and limits the amount of SWY and CWY which may be used. Frankly, I don't know if the FAR and JAR require the application of RESA, I've always applied the Australian RESA criteria for this consideration when working under these rules. (I love conservatism).

Regards,

Old Smokey

john_tullamarine
26th Jul 2010, 07:14
Is there a limit to the extent of a stopway?

Probably something hidden away in the bowels of the airport design standards. I'll run the question by OverRun who knows about such things.

I'd appreciate your naming the one airport you found

Probably a NSW/QLD country aerodrome as I recall -it was for a third level operator - 30 seat style of aircraft - long time ago now so the recall is a tad faded. I have a picture in my mind of the relevant runway terminating at a cross runway.

de facto
26th Jul 2010, 07:20
Dear JT,Old Smokey,

Apologies for the drift but could you please tell me the Minimum LEGAL flaps retraction altitude for ICAO?
I know FAA and JAA is 400ft.
If you have a document with your answer thatd be great:ok:

NotaLOT
26th Jul 2010, 12:46
Dear All,

Thank you for the replies, the picture is becoming a little clearer. So in essence, it all depends on whether TOW is currently ASDA limited.

As far as I understand it, for this particular runway, the TODA=TORA because of lack of a clearway (due to obstacles), although there is plenty of concrete to ensure an ASDA that is greater than TORA/TODA.

Thanks again!

Old Smokey
27th Jul 2010, 11:46
Hello NotaLOT,

Be careful, your remark it all depends on whether TOW is currently ASDA limited had me a bit worried.

ASDA is a purely physical dimension of the Runway characteristics. It is not related to aircraft performance.

ASDR (Accelerate-Stop Distance REQUIRED) is an aircraft performance limitation and "fits" your worrying statement. If ASDR=ASDA, then the aircraft is performance limited.

By the way, I fly over your part of the world quite often, which airport are you talking about where ASDA>TODA?

Regards,

Old Smokey

OverRun
28th Jul 2010, 03:59
I'm of the same mind as Old Smokey: "I've never seen ASDA>TODA, perhaps as J_T suggests, it may exist in rare circumstances."

I've had a good re-read of ICAO Annex 14 on stopways, and there is no airport induced limit in length for the stopway. The concept of TORA=TODA, and a longer ASDA is clearly contemplated in ICAO Annex 14. The picture from it should appear below (see example C):
http://profemery.info/stopway.jpg

This example is not usually seen in Australia because usually TODA is the full length of the runway plus the length of any clearway. What we do, where there is no designated clearway, is that the part of the runway strip between the end of the runway and the runway strip end is included as part of the TODA. In Australia, this distance is usually 60m, and so the TODA is usually 60m longer than the TORA. This Australian practice has been registered with ICAO. Any stopway is not involved.

I guess some other States do not include this part of the runway strip between the end of the runway and the runway strip end as part of the TODA; hence the ICAO example C in the picture above. This may be the case for NotaLOT.

Please note my frequent use of the word 'usually' in the above. As JT said Not always useful to try and generalise in performance work ...

The stopway concept in ICAO seems to be that:
a) it can be of lesser strength than the runway
b) it has to be as wide as the runway
c) it must be included in the runway strip.
d) the stringent gradient limits for the first/last quarter of the runway need not be applied.

I can see an advantage using a stopway where the ground is rather uneven (saves on earthworks and levelling), and I can see an advantage where the subgrade is soft and the runway pavement is very thick (reduced thickness). I have looked professionally at some Greek airports recently where it could be of real use. The savings could be worthwhile – certainly it would repay a bit more effort at design stage.

But it is rarely seen in modern airport engineering practice. I speculate that this may be a consequence of de-skilling in the design office, or perhaps it is a consequence of airports outsourcing their engineering to design firms who enjoy getting their design fees paid as a percentage of total construction cost. If they do less work for their fees and don’t refine the design by including stopways, and they reluctantly increase the total construction cost by spending more on earthworks and pavement, well . . . . .

Turning back to NotaLOT's case, I've got a thought for a gentle check. ICAO requires the stopway to be within the runway strip – which means that the obstacles might mean that the runway strip is limited in length and thus preclude a long stopway . . . .

NotaLOT
28th Jul 2010, 08:13
Hi Old Smokey,

I take your point about ASDA v ASDR, it is what I meant, but perhaps not expressed precisely enough.

The runway concerned is Rwy 11 at Warsaw Airport, where, according to the AIP, the following declared distances are listed:

TORA = TODA = 2300m
ASDA = 2597m

There is no stopway or clearway for this runway.

Regards

mutt
28th Jul 2010, 08:36
There is no stopway or clearway for this runway. 2597-2300 = 297 meters, what is this distance called?

O_S with the fleet replacement of the Classic and MD90, we are getting dragged kicking and screaming into the optimum world :):):) But at least we still have the MD11 which doesn't account for a Stopway or Clearway :):)

Our logic on the older aircraft was that they didn't have any allowance for line up nor did they have the ability to stop! Remember that these are aircraft were certified with NEW BRAKES and TIRES!

FE_Hoppy. The performance limit for the stopway is half the takeoff flare distance.

As for airports with ASDA > TODA, look at Peshawar in Pakistan, it has a stopway but the trees surrounding the runway prevent it being used as a clearway.... (Unless they chopped the trees down recently :)) Its also a novel runway in that it has a train track crossing it!

Mutt

NotaLOT
28th Jul 2010, 08:47
It's called about 300 meters Mutt :)

But seriously, there is no clearway or stopway declared in the AIP for that runway, so I am not sure what you would call it!

john_tullamarine
28th Jul 2010, 10:32
The performance limit for the stopway is half the takeoff flare distance.

Some clarification for those who might be confused by this statement.

Distance to liftoff must be such that at least half of the distance from liftoff to screen (takeoff flare distance) is over the TORA. Hence one can only schedule half of the flare distance beyond the TORA and into the TODA which provides the practical limit on clearway.

The BCAR rules used 1/3 rather than 1/2 but that is probably of little interest to anyone these days.

Generally we would cite clearway rather than stopway for the second part of the takeoff flare .. but, no matter.

we still have the MD11 which doesn't account for a Stopway or Clearway

I always had a suspicion that no-one at Long Beach had any concept of stopway or clearway.

ant1
28th Jul 2010, 11:11
mutt: I guess you meant "the performance limit for the clearway is half the takeoff flare distance".

Stopway can reach to the infinite and beyond but remember, as I previously posted, that you gotta have V1<=Vr

john_tullamarine
28th Jul 2010, 11:23
the performance limit for the clearway is half the takeoff flare distance

Loosely based on this, as I recall, there is an airports standards recommended maximum clearway .. there will be several threads where it's cited. However, unless the takeoff is TORA limited, most times it's not all that relevant.

ant1
28th Jul 2010, 11:48
JT, TORA limited is a new concept for me (or am I too tired today?). I agree TORA is very limiting. I always like to roll on concrete until lift off ;). Did you mean TODA or am I missing something?

john_tullamarine
28th Jul 2010, 23:28
TORA limited is a new concept for me

.. you and a lot of pilots.

If one lined up a thousand pilots (who hadn't done Perf A or similar training) I venture to suggest nearly all would look blankly at the person who mentioned TORA ...

Quick, heads up brief ..

(a) ASDA tries to set it up so you can stop on the hard stuff if it all turns to custard on the initial part of the journey

(b) TORA tries to get you off the hard stuff BEFORE the end of it - we try not to run on into the mud in the overrun before liftoff (except, occasionally, on 27 at MEL)

(c) TODA tries to get you over the fence (trees, whatever) without hitting it (them)

All of the above can look at the AEO or OEI cases.

My use of "tries" is intentional. There are no guarantees with this stuff in the limiting case .. but the probability of success, as demonstrated by the history, is pretty high.

ant1
29th Jul 2010, 15:06
Uuh, I think I get it. The way I was seeing was: if you don't make TORA you won't make TODA but thinking twice, that is not necessarily true. I'm one of the few then who's done class A and did not get it on first attempt. ;)

ant1
29th Jul 2010, 15:25
I will not delete otr modify the previous post although after some thought I continue to belive that if you don't make TORA you won't make TODA i.e. you are TODA limited.

I'll try to elaborate:

If you don't have enough TODA pavement then you continue rolling on the clearway then rotate and lift off. Even if you manage to make the screen height all your take off flare distance will have been over the clearway which is a no-no (1/2 flare dist limit).

Am I still missing anything?

john_tullamarine
29th Jul 2010, 20:21
This is a good diversion. You have done Perf A - hence you have a start to a reasonable grasp of the subject - such discussions on PPRuNe are a useful vehicle to knock off the rough edges.

For the majority of the younger pilot set, I suspect that performance doesn't go much past learning how to look up the RTOW tables on the flightdeck whilst on the ramp. Certainly, if that not be the case, then a lot of folk were asleep during their performance lectures. For the airline with which I started out, the Ops Engineers did all these lectures and the folk got quite a bit of over and above information .. albeit that many never quite got their heads around the nitty gritty.

If you don't have enough TODA pavement ....

TODA generally comprises the whole runway PLUS the clearway. Clearway usually is not pavement and, most definitely, is NOT for mixing with heavy aircraft bogies. It is not a case of having enough TODA - rather, you limit the TOW such that the TODR ≤ TODA. If you don't do this you are outside the AFM rule book requirements.

then you continue rolling on the clearway

I really hope that folk don't want to do this - against the rules and pretty foolhardy .. you MUST plan the numbers on the basis of being airborne some distance PRIOR to the end of the declared TORA.

then rotate and lift off

liftoff MUST occur not further along than that point in the declared TORA which will constrain the first half of the airborne distance to screen to be located over the TORA ie you MUST always be airborne BEFORE the end of TORA - the runway sealed bit.

all your take off flare distance will have been over the clearway which is a no-no (1/2 flare dist limit).

No - you are missing the important distinction - only a portion of the flare will be located over clearway and then only if you are running with an unbalanced takeoff schedule - TORA doesn't extend into the clearway bit. For a balanced field approach to the problem, clearway is irrelevant and doesn't come into the discussion at all.

However, please do continue the discussion - the aim is to air these sorts of things especially for the benefit of the newchums who often don't get any of this stuff in their training.

ant1
29th Jul 2010, 20:52
I did perf A during my frozen ATPL days and I would have to remove a thick layer of dust before daring to touch those files. That may explain it. After that though, I have digested a few CDs and PPTs.

If you don't have enough TODA pavement ....

Sorry, temporary disconnection between fingers and mind. I meant "If you don't have enough TORA pavement ...."

I see I was not successful in conveying -possibly due to the initial mispelling- that the rolling on the clearway part was purely a theoretical exercise.

I'll try that again. My understanding is that TORA limited means you are unable to lift off before the end of the pavement (TORA). What I reckon is before you are TORA limited you are already TODA limited.

Example: TORA=TORR+1m => TODA limited (You are TODA limited before being TORA limited).

Although I could be wrong I am far from seeing it.

john_tullamarine
29th Jul 2010, 22:49
Peace be upon you, my son .. the aim is to clear the cobwebs for the benefit of whomever might chose to follow the thread ... absolutely essential that we all accept that none of us knows more than a few of the answers ... and can learn more, day by day.

TORA limited means you are unable to lift off before the end of the pavement (TORA).

Not quite ... you have to be off the pavement AND halfway to screen height by end of the TORA. If that is the limiting T/O calculation then, indeed, you are TOR-limited. Note that, if you needed to go further than the TORA then you are OVER your TOR limiting weight and in trouble. Unfactored TODR is the distance at which you get to screen height.

What I reckon is before you are TORA limited you are already TODA limited.

Not at all the case - Type/runway dependent. Not a generalisation which can be made

Example: TORA=TORR+1m => TODA limited (You are TODA limited before being TORA limited).

Why should that follow ? You can easily be TOR limited and not TOD limited for a given runway ? Similarly, you may be under the TOR limiting weight, as well as under the TOD limiting weight and routinely be ASD limited, for instance ... or limited by some other consideration.

Although one gets a bit of a feel for a given Type after a while, philosophically, ALL the calcs are run and the lowest weight comes up trumps for RTOW.

Absolutely no reason why any case should, necessarily, have the inside running. Having said that, for a given Type, one will see a skewing of the results such that the limitation may well be ABC more often than not .. but the next Type may be quite different in its results.

This is one of the problems which confuses the student greatly when many training organisations attempt to condense the subject matter down into rules of thumb ... which often need a bunch of caveats added for the discussion to make sense.

ant1
29th Jul 2010, 23:41
After dusting off some material I found out what you already pointed out which is that 1/2 the air distance belongs to the TOR.

In this case it my example was inapropriate. I have always assumed that the field limited weight was the smaller of the TODA limited and the ASDA limited weight.

At least I have an excuse to go through all that stuff once more:

Love and peace.

PS: I wonder what DOB I put on my profile which has induced you to think I could be your son. I'll check that too. ;)

john_tullamarine
30th Jul 2010, 01:12
I have always assumed that the field limited weight was the smaller of the TODA limited and the ASDA limited weight.

almost .. the minimum of TOR, TOD and ASD limited weights. One of the reasons that this is not understood, generally, is that the majority of OEMs combine some of the AFM data and often TOR is not shown explicitly. Good British machines, on the other hand, tend to let it all hang out in all its glory ...

I'll check that too.

I was tempted to come back with a cheeky response but that probably would lower the tone of things .... best regards to you, good sir, and best of good fortune with your career.

Sir George Cayley
30th Jul 2010, 17:22
Just had a look at Google Earth for WAW. Has anyone else noted the humonguos displaced threshold on the recip RWY 29?

Suggests to me that there's an obstacle forcing the TOCS back up RWY 11.

Can see a railway line crossing and a built up area beyong which appears t include hi-rise housing.

Sir George Cayley

OverRun
31st Jul 2010, 10:45
Greetings Sir George. You've stimulated me to fire up Google Earth and take a look at this runway. I haven't checked the obstacles as you have, but I noticed something else.

I surmise that the full length of WAW runway 11/29 was used in the old days; and I measured this as 2800m (which is a nice round credible number). I also observe the concrete pavement slabs over 200m at each end of the full runway, and this is the normal position that an airport engineer would place them covering the start of the takeoff roll (since concrete is better than asphalt in supporting slow moving or stopped aircraft. It costs more than asphalt, so after 200m, the concrete is replaced by asphalt. That's why so many aprons are concrete while their runways are asphalt). I also observe the taxiway layout is such that there is a taxiway at each end of the full runway length. Could this be a cavalier [sic] military design without regard to civilian niceties?

So why did they shorten it now, and publish the odd ASDA and TORA/TODA figures?

Looking at the 'stopway' at the 29 end of 11/29, and then using the magic of Google Earth to tilt the picture [shift-down arrow keystroke] until it is almost flat, the very undulating nature of the terrain becomes clear. And the original designers have clearly done nothing by way of earthworks to provide a level runway. They simply laid it on the ground and it goes up and down as the ground goes up and down. Just east of the main (new/proper) runway end line and the big piano keys, the runway dips sharply. This dip is just beyond the declared TORA/TODA, and I am sure this bit of runway doesn’t meet ICAO requirements for runway or strip gradients (especially runway end gradients). Someone has picked the problem up on audit, and made the airport adjust their declared distances.

My guess is that the runway AND strip have then been arbitrarily terminated at the new runway end at 2300m (because of the gradient issues beyond that). There is still plenty of good runway and plenty of clear runway strip to the east BUT it doesn’t meet the ICAO rules except if used as a stopway. Thus the TORA = TODA = 2300m. And ASDA = 2597m.

The 2597m ASDA stops when the runway changes to concrete. It complies with ICAO because there is good runway and cleared strip out to that distance (just a bit steep gradient wise). I suspect that beyond it, the concrete is in really poor condition and not suitable for aircraft. I see a couple of concrete slabs have been replaced at WAW, and I have experience elsewhere of old Soviet military airfields and their teeth-rattling concrete slabs. . . .

My guess is that these odd declared distances are a clever bit of juggling by an astute engineer to squeeze the most out of a difficult situation.

Cheers,
Overrun

NotaLOT
31st Jul 2010, 12:32
Hi Overrun,

I am not sure about the gradients being non-compliant, since departures regularly use the full lenght distance (2800m) when departing on 29. However, I am sure the fact that the 29 threshold is at the bottom of the slope worsens the obstacle situation for approaches on 29 and departures on 11, and I believe this is the main reason for the threshold displacement for approaches on 29 and why on 11 the TORA and TODA are limited to 2300m (clearly obstacles not such a big issue for ASDA :))

Also I believe the ASDA for 11 is less than 2800 because the remaining distance is a RESA (can't get the RESA further out east because of the mound which acts as blast protection).

Mikehotel152
31st Jul 2010, 12:33
A very interesting thread. I read it as an inexperienced 738 driver who passed (and enjoyed) Performance during the ATPL theory exams, but always wondered how it relates to the real world.

OverRun's explanation of WAW certainly makes good sense. Thanks for that. :)

mutt
31st Jul 2010, 17:35
RWY 11 TORA 2300 ELEV 110M SLOPE -0.33
RWY 29 TORA 2800 ELEV 103M SLOPE +0.27

This is taken from a database which uses the difference in runway end elevation divided by length to get the slope. As its not one of our regular airports, no one has actually walked the runway. Maybe this airport proves that the concept of just using runway ends isn't always the correct approach.

Mutt

Pugilistic Animus
31st Jul 2010, 19:18
YouTube - Benny Goodman Quartet 1967 - w/Gene Krupa (http://www.youtube.com/watch?v=DfQA1DaNoBI)

having followed this thread from the beginning: this really does belong here;):D:ok:

FE Hoppy
31st Jul 2010, 19:43
PA

It's taken me 5 minutes to stop crying with laughter.
:ok:

john_tullamarine
1st Aug 2010, 01:59
Maybe this airport proves that the concept of just using runway ends isn't always the correct approach.

Which is why some up us never use this other than for runways with reasonably even slope ... just a matter of checking out the centreline longitudinal section survey data .. usually available.

The need is to overlay the actual aircraft performance on the section survey so that one doesn't, eg, run the ASDA with a totally inappropriate slope ...

Old Smokey
1st Aug 2010, 05:56
Mutt's comment - "Maybe this airport proves that the concept of just using runway ends isn't always the correct approach" is very valid, and J_T (as usual) beat me to the response.

In my performance work, I take a conservative approach to what I term "Composite Slope" runways. I stand by for incoming klak for being too conservative, but this is the technique that I employ in generating RTOWs -

For each runway, I run 3 analyses for each Takeoff consideration, i.e,

(1) The RTOW for the Mean Slope,

(2) The RTOW for the greatest UP slope, and

(3) The RTOW for the greatest DOWN slope.

The applicable limit (Accelerate-Go, Accelerate-Stop, MBE, etc.) is then the LEAST of the limits found. Many pilots don't notice, but one management pilot asked my why, for the same runway, the Slope printed on the RTOW was different for Full Length Vs Intersection departure - The answer; composite Runway Slope. Now throw in a few other factors such as CWY and SWY slope differing from the "Main" Runway slope (The EPWA case), and the runway becomes interesting.

My "mind set" began when once holding at the takeoff point waiting for an aircraft (B747) taking off in the opposite direction (Actually Mutt, it was one of yours, definately no criticism of you). It was (and is), a significantly humped runway, both ends the same elevation, thus Zero mean slope, but significant UP slope to the centre, followed by significant DOWN slope to the end. The said aircraft faced a degraded Takeoff performance, due to the actual Takeoff being UP slope instead of Zero, and a significant detriment to Accelerate-Stop due to DOWN slope if such a thing had happened (it didn't). The main gear cleared the runway end by just a few feet.

Yes Mutt, I do agree with you, the concept of just using runway ends isn't always the correct approach, there is an alternative, however conservative it may be.

Regards,

Old Smokey

mutt
1st Aug 2010, 10:07
O_S for regular airports we actually follow your method. For example in Manila the final portion of he runway slopes up more than average, so we use this value and accept the resulting 3000 kgs payload drop.

The older 747 is generally limited by all engine go, hence this is one of the reasons that you see them almost scraping the lights.

Mutt

Old Smokey
1st Aug 2010, 11:46
Mutt, I'm happy to see that I have a fellow traveller in applying this conservative approach...:ok:

The said flight was indeed one of the early B747s, loaded to the gunnals for a Haj flight direct to home.

Payload penaltys of the order of 3,000 Kg are indeed significant, but I sleep better at night knowing that I've delivered my end users (the pilots) with information which errs on the side of safety, presumably you do too:ok:

Now that most of our B777 ops are based upon performance calculations derived from the EFB OPT, Heaven only knows what "precautionary" measures the programmers have incorporated......probably none!:eek:

BTW, welcome to the world of unbalanced field operations, happens to the best of us.:D

Regards,

Old Smokey

mutt
1st Aug 2010, 19:38
unbalanced field operations ha ha, not I, totally balanced operations these days :):)

Mutt